Good Riddles

Question: I can hurt you unbearably and can't be touched. What am I?

Question: Sophie who is a housemaid, knows her boundaries well. She is good at equations. Her favorite vegetable is cauliflower. Which is her favorite plant?

Question: What speaks with its ear, listens with its mouth, and has 10 digits but no hands?

Question: What goes black when you buy it, red when you use it, and goes white when you throw it away?

Question: You use me. I keep you neat. Every once in a while you empty me out. What am i?